Semiconductor devices such as an LED and a power module have a structure in which semiconductor elements are bonded to an upper surface of a circuit layer made of a conductive material.
A high-power control power semiconductor element used to control wind power generation systems and electric vehicles such as electric automobiles radiates a large amount of heat. For this reason, in the related art, a power module substrate, in which a metal plate with superior electrical conductivity as a circuit layer is bonded to one surface of a ceramic substrate made of aluminum nitride (AlN) or the like, is widely used as a substrate on which such power semiconductor elements are mounted. In another type of power module substrate, a metal plate as a metal layer may be bonded to the other surface of the ceramic substrate.
A power module substrate disclosed in PTL 1 has a structure in which a circuit layer is formed by bonding a Cu foil (Cu member) to one surface of a ceramic substrate (ceramic member). The power module substrate is formed by bonding the Cu foil to the ceramic substrate through the heating of the Cu foil which is disposed on the one surface of the ceramic substrate with a Cu—Mg—Ti brazing filler material interposed between the Cu foil and the ceramic substrate.